Tibiofemoral Joint Forces during the Stance Phase of Gait after ACL Reconstruction

The main goals of anterior cruciate ligament reconstruction (ACLR) are to restore knee function and prevent development of osteoarthritis (OA). However, the incidence of early-onset OA remains higher in patients following ACLR. The purpose of this study was to compare the computed tibiofemoral joint (TFJ) forces and muscle forces of ACLR knees to those of BMI-matched control subjects during the stance phase of gait. We hypothesized that the use of principal component analysis would allow us to characterize alterations in three-dimensional TFJ loads and muscle forces after ACLR as compared to a healthy control population. Of the eight ACLR knees, four displayed an abnormal TFJ compressive force. In three of these four ACLR knees that displayed abnormal compressive forces, one of the major muscles/muscle groups crossing the knee also deviated from the control group. We believe that each subject has a unique response to their injury, reconstructive surgery, and rehabilitation.

<i>In vitro</i>measurement of tibiofemoral kinematics after patient-specific unicompartmental knee replacement

It is suggested that unicompartmental knee replacement (UKR) offers the potential to restore normal knee kinematics better than total knee replacement (TKR) because of retaining the cruciate ligaments, and better preservation of the overall geometry. It was hypothesized that patient-specific UKR would restore normal knee kinematics even better because of a customised articular shape. A comparative kinematics study was conducted on three cadaver limbs using two different test setups, a loaded ankle rig and an unloaded ankle rig. Kinematics was compared between a patient-specific UKR and a conventional fixed-bearing UKR. Both the UKRs showed similar kinematic patterns to the normal knee using both the test apparatus. The patient-specific UKR showed good results and with the other benefits it shows potential to dramatically improve clinical outcomes of knee replacement surgery.

Traumatic Neglected Antero-Medial Knee Dislocation: Case Report

Introduction: Neglected knee dislocation is an unusual injury, only a few cases have been reported in the literature. The circumstances of onset are generally an unnoticed knee dislocation in a polytrauma context or a delay in consultation after the initial trauma. Presentation of case: We report the case of a 48-year-old female patient who sustained a knee injury during a domestic accident. Initial treatment was traditional and was followed for 3 years. She then consulted hospital, where a neglected knee dislocation was identified and treated with femorotibial arthrodesis. Discussion and conclusion: The treatment options of neglected knee dislocation include open reduction and fixation, arthrodesis and total knee arthroplasty. That the choice depends on the old unreduced of dislocation.

A New Computer Assisted Orthopaedic Surgery System:WATO

Background:The traditional manual orthopaedic technology heavily relies on a surgeon's experience,so it certainly increases the instability of the surgery.Therefore,computer assisted orthopaedic surgery(CAOS) is becoming a hot research topic for its high accuracy and stability.We developed a new CAOS system WATO,which is mainly designed for total knee replacement(TKR).Methods:WATO system provides the interactive software for a surgeon's preoperative planning.Based on its two infrared cameras,infrared markers and infrared probe,WATO system gives a simple surgical positioning procedure of femur and tibia without additional surgery for the placement of fiducial markers.According to the reference alignment axis from positioning procedure,a surgeon can move the robot of WATO system to do accurate bone resection.Safety checking is also considered in WATO system.Results:Extensive experiments were conducted on phantoms and cadaver bones to verify the accuracy and stability of WATO system.Experimental results showed that TKR using WATO system had better performance compared with traditional and navigated TKR.Conclusion:WATO system shows its superiority in TKR,and has a broad application prospect in the future.We will develop its new functions for other orthopaedic surgery such as total hip replacement(THR).Current disadvantages such as bigger skin incision have to be resolved in the future.

Short Leg Film Is Sufficient for Postoperative Follow-Up in Total Knee Arthroplasty

The gold standard for evaluating postoperative alignment after total knee arthroplasty (TKA) has been standing AP hip to ankle radiograph. The objective of this study was to determine if the angle between the anatomic axis of the tibia and femur measured on short standard radiographs accurately reflected overall coronal and mechanical alignment from full length knee films. Both full length and short length knee films were retrospectively compared measurements made on from 188 knees in 129 consecutive patients after primary TKA between July 1990 and January 1991. The tibiofemoral angle, distal femur and proximal tibia resection angles, and mechanical alignment were evaluated on the long leg by a blinded observer. The difference in the tibiofemoral angle measured on short and long leg films, 4.4 (+/﹣2.9) vs 5.2 (+/﹣3.0) degrees of valgus, respectively, was statistically significant (p < 0.01). The correlation coefficient between the tibiofemoral angle and mechanical axis was 0.9 (p < 0.01). There was no difference in the distal femur or proximal tibia resection angle measured on short length knee vs long leg films. In conclusion, the tibiofemoral angle measured on short length knee radiographs accurately reflects postoperative alignment. The differences between tibiofemoral angle and the mechanical alignment are highly correlated and equivalent measures of overall alignment.